Ultra-low temperature refrigerators are often referred to as cryogenic storage boxes, ultra-low temperature freezers, cryogenic storage boxes, and the like. Ultra-low temperature refrigerators are essential for biochemistry and molecular biology laboratories and are used primarily for the preservation of biological samples or pharmaceuticals. Ultra-low temperature refrigerators range in temperature from -40 ° C to -150 ° C. Ultra-low temperature refrigerators have a wide range of applications, such as biological research, metal processing, hospitals, epidemic prevention systems, and military applications. Ultra-low temperature refrigerators can be used for vaccines, enzymes, hormones, stem cells, platelets, transplanted skin, specimens taken from the human body, germplasm banks of plant seeds, gene clone libraries, and some important biological and chemical reagents, as well as industrial research and development.